Senator Richard Burr stepped aside as chairman of the Senate Intelligence Committee on Thursday after the FBI served a search warrant for his phone as part of an ongoing insider-trading investigation tied to the coronavirus pandemic.
Senate Majority Leader Mitch McConnell announced the move, saying he and Mr Burr had agreed it was in the Senate's best interests.
FBI officials showed up at Mr Burr's home with the warrant on Wednesday, marking a significant escalation in the Justice Department's investigation of whether the senator broke the law with a well-timed sale of stocks before the coronavirus caused markets to plummet,
The Justice Department declined to comment. Mr Burr's attorney did not respond to phone and email messages, but said last month that the law was clear that any senator could participate in stock market trading based on public information “as Senator Burr did".
Mr Burr has denied wrongdoing but has also requested an ethics review of the stock sales.
Senate records show that the senator and his wife sold stocks worth between roughly $600,000 (Dh2.2 million) and $1.7 million in more than 30 transactions in late January and mid-February, just before the market began to nosedive and government health officials began to sound alarms about the virus. Several of the stocks were in companies that own hotels.
Mr Burr has acknowledged selling the stocks because of the coronavirus but said he relied “solely on public news reports”, specifically CNBC’s daily health and science reporting out of Asia, to make the financial decisions.
Mr Burr's six-year term ends in 2023.